Heat exchanger



HEAT EXCHANGER 2 Sheets-Sheet 1 Filed Dec. 17, 1941 IN VENTORS HERMAN E BUSCHOW BY 1w 1 g zawnno GiE/VGEL mAm \m k ATTORNEYS y 1944. H. F. BUSCHOW ETAL 2,348,601

HEAT EXCHANGER Filed Dec. 1'7, 1941 v 2 Sheets-Sheet 2 v 45 4o 26 19 @IIIL! I4- 15 INVENTORS HERMAN F: BUSCHOW BY 1/ 1. ij fflwnm a. E/VGEL ATTORNEYS Patented May 9, 1944 2,348,601 'nnA'r EXCHANGER Herman F. Bnschow, New York, N. 12, and Edward G. Engel, Roselle, N. 5., assignors to The M. W. Kellogg Company, New York, N. Y., a corporation of Delaware Application December 17', 1941, Serial No. 423,254

.9 Claims.

This .invention relates to heat exchangers, and has particular reference to a type of heat exchanger wherein heat is transferred between two fluids through the agencyof a third fluid.

It is the usual practice in the heat exchanger art to effect a transfer of heat between two fluids by direct conduction through the walls of the vessel separating the fluids. For example, a high temperature fluid may be passed through a tube or nest of tubes encased within a larger tube or shell through which flows a lowei' temperature fluid. In such an arrangement, heat transfer occurs through the walls of the inner tube or tubes.

,Where it has been deemed impractical for any reason to combine in a single heat-exchanger unit two particular fluids, the practice generally has been to employ separate units and to utilize a third fluid as a heat transfer medium. For example, the thirdfluid may be made to pass through the first unit and to absorb heat from the fluid therein; the third fluid is then transfei'red to'the second unit where it gives up the stored heat to the fluid in the latter unit. A sysflow direction of the heat exchange fluids through Q encases a multiple coil system suitably supported This duplication matthrough the agency of a third fluid within a single vessel or shell.

A further object is to provide a heat exchanger adapted to effect an exchange of heat between two fluids through the agency of a third fluid in which the heat transfer rate may b'' regulated independently of the flow rates of the two fluids;

The further objects of this invention will become apparent from a consideration of the folpart of this application in which:

Fig. 1 is a sectional elevation of the heat exchanger with portions of the coil'system and the heat transfer liquid distributor broken away to more clearly reveal the structure; Fig. 2 is a section taken along line 2-2 of Fig. 1; Fig. 3 is a section taken along line 3-3 of Fig. 1-; Figs. 4 and 5 are fragmentary enlarged isometric views of the coils; and

Fig. 6 is a diagrammatic view showing a single on pedestals ll. Shell i0 is a cylindrical casing placed in upright position upon an annular base l2 of.concrete or other suitable material. The bottom of the shell is closed in a fluid-tight seal by horizontal plate I3 upon which pedestals H rest.

The coil system of the heat exchanger comprises a plurality of separate units connected in parallel' In the present embodiment, three units, generally indicated at l4, l5, and it are shown, although fewer or more may be employed.

Each coil unit l4, l5, and It comprises a pair of vertically spaced, interlocking, helical coils I1 and it of equal diameter and pitch. The coil units are arranged concentrically, as shown in Fig. 1. Suitable headers, hereinafter referred to, connect across the coil units to provide common inlets and outlets for the hot and the cold heatexchange media. The coil arrangement of a single unit is diagrammatically shown in Fig. 6.

Since the coil units have a similar arrangement, only one unit need be described. Coil IT. that is, the upper coil, is connected at its ends to multiple headers I91 and 2| which in turnconnect with a=vertical riser 22. Riser 22 extends downwardly through the plate l3 into the well 23 formed by the annular base l2, where it joins the supply conduit 24 for the high-temperature heat-exchange medium.

A multiple T-header 25 taps into the middle of coil IT to provide an outlet for the cooled medium. In other .words, two equal flow paths for the high-temperature medium are established within coil ll, flowing in opposite directions from the endstoward the center. Header 25 connects with a vertical return pipe 26 extending down-- wardl'y through plate l3 into well 23 where it joins outlet conduit 21. p Coil [8, the lower coil, is positioned so that each of its turns lies directly beneath a turn of coil ll.

Multiple headers 28 and 29 'at theends and a multiple T-header 3| at the center are provided,

as' in coil l'l. T-header 3| connects with a-riser unit of the heat exchanger and indicating the tions from the center toward the ends.

The two coils l1 and I8 thus provide wholly independent fluid paths for the hot and the cold media. Not sharing a common separating wall, as would be the case with the usual tube-withina-tube arrangement, each tube may be made of such material, and be so designed, as to provide the degree of strength, corrosion-resistance, eto., most suitable for the particular medium to be conducted and for the conditions of temperature and pressure under which it is made to flow. A leak occurring in onetube will not contaminate the fluid in the other tube, as would result when a leak occurs in the inner tube of a tube-withina-tube heat exchanger.

To eilect a transfer of heat between the fluids in coils l1 and I8, we provide an intermediate agency in the form of a liquid bath. This heat transfer liquid, which is preferably water, but may be any other liquid, is made .to course down over the entire coil system, alternat ely picking up and losing heat as it passes from a turn of the hot coil to a turn of the cold coil.

The heat transfer liquid is supplied from. a reservoir 36 supported within the upper portion of the shell Hi. The liquid falls freely from concentric shower rings 31 in the form of annular tubes having a row of openings 38 along their lower edge. The liquid in -reservolr 36 is supplied to the shower rings 31 through diametrically opposite tubular cross-arms 39. The heat transfer liquid collects in the bottom of the shell where a predetermined liquid level is maintained.

-The liquid in the bottom of the shell drains through a pipe 4| to a pump 42 placed in the well 23 by which the liquid is raised through a riser 40 to the reservoir 36.

In order to have the heat transfer liquid concentrated in avertical path as it courses down over the coils, means have been provided to minimize deflection or splashing of the liquid away from the coils. Along the lower edge of the coil tubing a downwardly'projecting ridge 43 is formed, as by welding or brazing a wire strip to the coilsurface. This is clearly shown in the enlarged fragmentary views of Figs. 4 and 5.

The ridge 43 causes the liquid flowing over the sides of the tubing to drip or flow centrally upon the turn of the coil below. As an additional aid in concentrating the stream of liquid, spray return guards 44 are attached to the coils, as illustrated in Fig. 5. The spray guards comprise a thin flat strip of metal joined along one edge to the surface of the tubing and extending upwardly and outwardly to gather in liquid falling away from the coil. The spray guard strips follow the coil helix for at least one full turn.

'To prevent the spray guards from cutting oil the flow of liquid down over the side of the coil to -'which they are attached, spaced openings 45 are provided between the guard strips and the coil surface. The release through the openings 45 of liquid tending to accumulate in the trough formed between the spray guards and the surface of the coil prevents the formation of a stream spiralling down along the trough.

The heat exchanger apparatus illustrated and described represents a'preferred embodiment of our invention. Depending upon the use to which it is put, the heat-exchange media it is to handle, and the conditions under which it is to operate, we contemplate various modifications in both the apparatus and its method of use. In particular, the word "coil" is not to be construed in its naragainst corrosion, we iniect an inert gas into.

the shell. The heat conducting properties of the metal coils are thus retained for a longer period of time.

It will be apparent to those skilled in the art that our invention is susceptible to various other changes and modifications without departing from the spirit thereof, and it is desired therefore that only such limitations shall be placed thereon as are specifically set forth in the appended claims. o Weclaim:

i 1. A heat exchanger comprising a shell; a plurality of concentric helical coils supported vertically within said shell; said plurality of coils having common inlets at the ends and a common outletat the center for a fluid heat exchange medium; a second plurality of concentric helical coils for a lower temperature fluid heat exchange medium, said second plurality of coils being substantially identical in size to, and arranged interlockingly on a common axis with said flrst plurality, the turns of each pair of interlocking coils alternating in spaced vertical alignment, said second plurality of coils having a common inlet at the center and common outlets at-each end; a supply of heat transfer liquid within said shell; concentric shower rings individual to and supported above-each of said pairs of interlocking coils to provide a cylindrical stream of said liquid coursing downward- 40 1y over each pair of coils; and means for returning said liquid from the bottom of said shell to said shower rings.

2. A heat exchanger comprising a pair 01 coils conducting a high-temperature and a low-tem- 4 perature fluid, said coils being disposed interlockingly with-their turns arranged alternately *in spaced vertical alignment, one of said coils having a flow from the ends inwardly to the center and the other having a flow from the center outwardly to the ends; a source of heat transfer liquid; and means for continuously directing a stream of said liquid upon the surface of the uppermost turn said liquid stream alternately absorbing heat from a turn of the high- 5 temperature coil and transferring it to a turn of the low-temperature coil as it courses freely down over the coil system.

3. In a heat exchanger, a pair of coils for conducting. two fluid heat-exchange 'media, said coils being disposed interlockingly with their turns arranged alternately in spaced vertical alignment; a source of heat transfer liquid; means for directing a stream of said liquid along the surface of the uppermost turn; and a depending strip centrally located along the under surface of said coils to direct the flow of said liquid from a turn of one'coil to the turn of the other coil immediately below.

4. In a heat exchanger, a pair of coils for conducting two fluid heat exchange media, said coils being disposed interlockingly with their turns arranged alternately in spaced vertical alignment; a source oi heat transfer liquid; means for directing a stream of said liquid along 7-F,the surface of the upp rmost turn, said stream passing downwardly over the coil system from a turn of one coil to the turn of the other coil immediately below; and spray guards for gathering in toward said coils liquid spraying away from said stream, said spray guards comprising flat strips attached at their edge along at least one turn of said coils and projecting upwardly and outwardly from the coil surface.

5. In a heat exchanger, a pair of coils for conducting two fluid heat-exchange media, said coils being disposed interlockingly with their turns arranged alternately in spaced vertical alignment; a source of heat transferliquid; means for directing a stream of said liquid along the surface of the uppermost turn; a depending strip centrally located along the under surface of said coils to direct the flow of said liquid from a turn of one coil to the turn of the other coil immediately below; and spray guards for gathering in toward said coils liquid spraying away from said stream, said spray guards comprising flat strip attached at their edge along at least. one turn of said coils and projecting upwardly and outwardly from the coil surface.

6 A heat exchanger comprising a pair of coils for conducting two fluid heat-exchange media,

turns arranged alternately in spaced vertical alignment; a source of heat transfer liquid;

means for directing a stream of said liquid along the surface of the uppermost turn; and a depending strip centrally attached along the under surface of said coils to direct the 'flow of said liquid from a turn of one coil to the turn of the other coil immediately below.

'7. A heat exchanger comprising a pair of coils for conducting two fluid heat-exchange media, the high-temperature coil having a flow from the ends to the center and the low-temperature coil having a flow from the center to the ends, said coils being disposed interlockingly with their turns arranged alternately in spaced vertical alignment; a source of heat transfer liquid; means for directing a stream of said liquid along the surface of the uppermost turn; 2. depending 5 strip centrally attached along the under surface of said coils to direct the flow of said liquid from a turn of one coil to the turn of the other coil immediately below; and spray guards for gathering in toward said coils liquid spraying away from said stream, said spray guards comprising-flat strips attached at their edge along at least one turn of said coils and projecting upwardly and outwardly from the coil surface.

, 8. A heat exchanger comprising a closed shell. a pair of coilsfor two fluid heat-exchange media supported within said shell and disposed interlockingly with their. turns arranged alternately in spaced vertical alignment, the upper coil having a flow from the ends inwardly to the center and the lower coil having a flow from the center outwardly to the ends; a supply of heat transfer liquid at the bottom of, said shell below said coils: a reservoir supported above said coils: outlet means from said reservoir adapted to di- 5 rect a stream of said liquid upon the surface of the entire uppermost turn; means attached to said coils for guiding the downward flow of said liquid; and means for returning said liquid from the bottom of said shell to said reservoir.

' 9. A heat exchanger comprising a vessel, a source of heat transfer liquid, means forming a stream of said heat transfer liquid within said vessel, a pair of coils within said vessel for conducting two heat exchange fluids, said coils being placed within said stream in such manner that said heat transfer liquid passes from endto end over each coil altematingly contacting first a turn of one of said coils and then a turn of the other, the flow of heat exchange fluid in one coil being from the center outwardly to the ends and in the other coil from the ends inwardly to the center. v

' HERMAN F. BUSCHOW.

EDWARD G. ENGEL. 

